In accordance with the present invention, there is provided a reaction product of a sulphurized olefin and a thiadiazole derivative.

The reaction is preferably carried out in two distinct stages: -stage one involves the reaction of an otefin with sulphur to produce a sulphurized olefin; and -stage two involves the reaction of the sulphurized olefin produced in stage one with a thiadiazole derivative. In stage two, the thiadiazole derivative actually reacts with the sulphurized olefin. (By this, we mean that the thiadiazole derivative does not act as a catalyst.) The thiadiazole derivative is preferably a mercapto-thiadiazole derivative. The mercapto-thiadiazole derivative is preferably a DMTD 4-thiadiazole) derivative.

In accordance with the present invention there is also provided use of the reaction product defined above as a multifunctional component in lubricants.

In accordance with the present invention there is also provided use of the reaction product defined above as an antioxidant, a copper passivator and/or an extreme pressure additive.

The sulphur content of the sulphurized olefin is preferably between 5 and 40%, more preferably between 7 and 12%, even more preferably between 6 and 9%, and most preferably around 8%.

The sulphurized olefin is preferably a sulphurized a-olefin.

The sulphurized olefin can be prepared from an a-olefin such as, for example, a C6., a-olefin, that is sulphurized by heating the a-olefin in the presence of sulphur.

The heating is preferably conducted between 120 and 200°C for four hours, even more preferably between 140 and 170°C for four hours The ratio of a-olefin to sulphur is preferably from 75 : 25% to 99 : 1%.

Suitable commercially available sulphurized α-olefins are: HSI-20 from Kiel Chemicals or RC-2540 from Rhein Chemie The DMTD derivative may be represented as follows : where R and R, can be the same or different and are hydrogen or Ci to C30 hydrocarbyl selected from alkyl, aryl, aralkyl, alkaryl and may optionally contain addition O, S or N or mixtures thereof. Preferably R is CnH2n. 11 and n is 1 to 30.

The DMTD derivative may be prepared by the reaction of DMTD with a hydroxycarbyl mercaptan and hydrogen peroxide ; or by the reaction of hydrazine with carbon disulfide, oxidatively coupled with alkyl mercaptans. Reference is made to CA 1 232 277 and WO 96/06903 respectively.

Alternatively, the DMTD derivative can be obtained from, for example, Vanderbilt Company, Ethyl Corporation and Rhein Chemie. Suitable commercially available DMTD derivatives are: HITEC 4312 and 4313, available from Ethyl Corporation; Cuvan 826, available from Vanderbilt Company ; or RC 8210, available from Rhein Chemie.

The sulphurized a-olefin and the DMTD derivative are preferably reacted using from 92-97%, preferably 95-96%, of a-olefin with from 3-8%, preferably 4-5%, DMTD derivative.

The reaction is preferably run from 15 minutes to 4 hours, more preferably 1-3 hours, even more preferably 1.5-2.5 hours, and most preferably around 2 hours.

The reaction is preferably conducted at a temperature between 60 and 150°C, more preferably between 80 and 130°C, and most preferably between 100 and 120°C.

The reaction product is preferably dark brown in colour with a viscosity of between 4 and 12 cSt at 40°C. The reaction product is preferably readily soluble in mineral base oils and/or synthetic hydrocarbons (e. g. ester-based fluids, poly a-olefins, poly isobutenes and fatty acid esters). The reaction product preferably has a specific gravity of between 0.7 and 0.9 at 29°C. The flash point of the reaction product is preferably between 80 and 120°C, more preferably between 85 and 95°C, and most preferably around 90°C. The reaction product is preferably thermally stable at low temperatures, i. e. between 0°C and 50°C.

The reaction product may be used as a multifunctional component in lubricant oils.

The reaction product is preferably used as an antioxidant, a copper passivator and/or an extreme pressure additive.

The reaction product may be incorporated into a lubricant in an amount from at least 0.01 wt%, preferably from 0.1 to 10 wt%, more preferably from 0.1 to 0.5 wt%, and even more preferably from 0.2 to 0.5 wt%. The base oil in the lubricant may be natural or synthetic. The following usual additives may be incorporated into the lubricant: dispersants, detergents, corrosion-inhibitors, VI improvers, antioxidants, EP additives, anti-wear additives, and friction modifiers.

The lubricant may be a neat (i. e. not water-reducible) metalworking fluid. In a neat metalworking fluid, the reaction product is preferably present in an amount between 2 and 10 wt%, more preferably between 4 and 6 wt%, and most preferably around 5 wt%. The neat metalworking fluid may also comprise a natural or synthetic base oil, and a lubricity agent, for example, esters of mono-and di-carboxylic acids, polymeric esters, sulphurized hydrocarbons, chlorinated compounds, anti-oxidants, anti-mist agents, and other components such as, for example, metal salts.

Additionally, phosphate esters, which act as anti-wear agents, and chlorinated hydrocarbons, which provide both extreme pressure and anti-wear properties, may be added.

The reaction product may be used in metalworking fluids to replace chlorine-based products. As a skilled person will know, chlorine-based products are environmentally unfriendly.

The lubricant may be a transformer oil, i. e. an oil used in transformers. In a transformer oil, the reaction product is present in an amount from 0.01 to 10 wt%, preferably 0.1 to 0.4 wt%, more preferably around 0.2 wt%. The transformer oil also includes a transformer oil base stock as a base oil. The reaction product can be used in transformer oils to improve electrical properties, for example, to improve resistivity at room temperature and at 90 °C, in accordance with ASTM D 3487 and BS 148 or Indian Standard IS 335; to provide a better reduction in TAN Delta; and to provide greater oxidancy. To obtain better results, the reaction product may be used in addition to conventional phenolic anti-oxidants, for example, 2,6-ditertiarybutyl Paracresol (DBPC) or butylated hydroxy toluene (BHT).

The lubricant may be an engine oil. The reaction product may be used in the engine oil in an amount between 0.1 and 10 wt%, preferably from 0.1 to 5 wt%, and more preferably in an amount around 0.25 wt%. The engine oil may also include: a synthetic or natural base oil; and additives selected from: detergents, dispersants, corrosion inhibitors, viscosity index improvers, pour point depressants and friction modifiers. The engine oil may be, for example, a passenger car engine oil, a gear oil, an automatic transmission fluid, a diesel engine oil and a marine engine oil.

The invention will now be described, by way of example, with reference to the following examples: Manufacture of the Reaction Product The reaction product is made in two stages : Stage 1 92 grams of a C, 2-, 4 a-olefin commercially available from Chevron Chemicals, USA, was placed in a suitable reaction flask which is fitted with an air blower, which is capable of micronising air, and which is also fitted with a suitable turbine-type stirrer. The olefin was heated to 120°C and 8 grams of flowers of sulphur, which is generally available as less than 300 mesh particle size, was added under constant stirring. The temperature was raised to 150 °C and held at that temperature. When the reaction took place, the temperature of the reaction mixture rose by 10 °C to 160 °C. Cooling water was circulated around the reaction flask to maintain the reaction mixture at 160 °C for four hours. At the end of four hours, the reaction mixture was checked for solubility in mineral oil and free unreacted sulphur (no sediment/debris).

The reaction mixture was also checked for copper corrosion using ASTM D130, which gives a value of greater than 3 (typically 4a).

Stage 2 95 parts by weight of the reaction product of stage 1 above was reacted with 5 parts by weight of a DMTD derivative (HITEC 4312, available from Ethyl Corporation).

The reaction was performed in a suitable reaction flask at 120 °C. The DMTD derivative was added slowly to the reaction flask while maintaining the reaction temperature at 120 °C and stirring continuously for between 45 minutes to 1 hour.

The reaction product was then cooled to room temperature and checked for: a) solubility in mineral oil, e. g. 5% by weight of the reaction product in 150 SN oil; and b) copper corrosion in accordance with ASTM D130, which typically gives a value of '1 b'or better.

Example 1-Use of Reaction Product as an Antioxidant 0.2% by weight of the reaction product prepared above was added to 150 solvent neutral base oil, available from Mobil. The oxidation onset temperature was measured using a pressure differential scanning calorimeter ('PDSC') at a pressure of 500 psi under an air atmosphere.

Details of the PDSC oxidation test are as follows:- Instrument: 910 model pressure DSC of TA Instruments, USA Gas: Air at 500 psi Pans : Aluminium pans Sample amount : 0.5 mg Programme: 1. Data storage off 2. Equilibrate at 60 °C 3. Data storage on 4. Ramp 50 °C per min to 350 °C The PDSC oxidation test produces a temperature-time curve, which is also known as a thermogram. The oxidation onset temperature is determined by drawing a tangent at the point of inflection of the temperature-time curve. The higher the value of the oxidation onset temperature (after addition of the reaction product), the better its performance will be as an antioxidant. A boost of 10 degrees or more is considered to be a significant level of antioxidant activity.

Results in PDSC Oxidation Test Sample Oxidation Onset Temperature 150 SN (Mobil) 199 °C 150 SN (Mobil) with 0.2% of the 223 °C reaction product prepared above The above results show that the reaction product acts as an antioxidant.

Example 2-Effectiveness of the Reaction Product as an Antioxidant The effectiveness of the reaction product as an antioxidant was compared to the effectiveness of known anti-oxidants: biphenyl amine derivatives and phenolic anti-oxidants. The biphenyl amine derivatives are: NAUGALUBE, available from Uniroyal; and IRGANOX L57, available from Ciba-Geigy. The phenolic anti-oxidants are : HITEC 4710, available from Ethyl Corporation; and Rhein-Chemie 7110, available from Rhein-Chemie Limited. The results at 0.2% treat levels were as follows: Sample Oxidation Onset Temperature Reaction roduct 223 °C NAUGALUBE640 222 °C NAUGALUBE 438 L 223 °C IRGANOX L57 222 °C HITEC 4710 221 °C The oxidation onset temperatures were measured in relation to untreated 150 SN (Mobil) having an oxidation onset temperature of 199 °C.

The above results show that the reaction product is as effective as commonly used, conventional anti-oxidants. The reaction product is therefore a new, alternative antioxidant.

Example 3-Use of the Reaction Product as a Copper Passivator The effectiveness of the reaction product as a copper passivator was measured using the standard method IP 154.

Comparative experiments were conducted using : a) 150 SN base oil (Mobil); b) 150 SN base oil (Mobil) with 10 ppm Sulphur powder and then with 25 ppm Sulphur powder; and c) 150 SN base oil (Mobil) with 10 ppm sulphur powder and 0.2% of the reaction product prepared above, and then with 25 ppm sulphur powder and 0.2% of the reaction product prepared above.

The results were as follows : Sample Copper Corrosion Test Results (IP 154) 150 SN base oil Mobil 1 a 150 SN base oil (Mobil) with 10 ppm 3b Sulphur powder 150 SN base oil (Mobil) with 25 ppm 4a Sulphur powder 150 SN base oil (Mobil) with 10 ppm 2a sulphur powder and 0.2% of the reaction product prepared above 150 SN base oil (Mobil) with 25 ppm 2d sulphur powder and 0.2% of the reaction product prepared above The above results show sustained copper passivation of the reaction product.

Example 4-Use of the Reaction Product as an Extreme-Pressure Additive Extreme pressure properties provide an indication of load bearing characteristics of lubricants. The higher the weld load, the better the load bearing characteristics.

Weld load is measured using a Four Ball EP machine in accordance with IP 239.

The results were as follows : Sample Weld load, Kg 150 SN (Mobil) base oil 130 150 SN (Mobil) base oil with 0.2% 140 reaction product 150 SN (Mobil) base oil with 0.5% 160 reaction product 150 SN (Mobil) base oil with 1.0% 180 reaction product The results show that the reaction product exhibits superior load bearing characteristics.

The reaction product was blended with a commercially available ester, propylene glycol dioleate (PGDO), and assessed for weld load as per IP 239. The result was compared with a blend comprising the same ester with a chlorinated compound, Cereclor 42L, available from ICI (UK).

The blend details were as follows: Sample Weld load, Kgs 3% ester + 1.5% reaction product in 200 300 burning oil 3% ester + 1.5% Cereclor 42 L in 300 175 burin oit The results show that the blend comprising 3% ester and 1.5% reaction product in 300 burning oil exhibits higher weld load.

It is noted that both blends were passive to copper in accordance with ASTM D 130.

Example 5-Transformer Oil A transformer oil is an insulating fluid used in electrical machines, e. g. transformers.

A transformer oil needs to conform to the standard properties listed under ASTM D 3487, BIS 148 or IEC 296. Two of the standard properties are resistivity at ambient temperature and an elevated temperature such as 90 °C, and'Tan Delta'at 90 °C.

It is desirable for the resitivity to be high and the Tan Delta to be low.

A base oil (85 SN, available from Mobil) will give the parameters that can be improved using an antioxidant.

We have found that the use of 0.2% of the reaction product can improve the resistivity and Tan Delta more than the use of 0.3% of a conventional antioxidant such as 2,6-ditertiary butyl paracresol (DBPC). Furthermore, a synergistic effect can be achieved with the use of 0.2% of DBPC and 0.05% of reaction product. Sample Resistivity @ Resistivity @ Tan Delta Total Acidity room temp 90°C @ 90 oc mg KOH/gm 85 SN Base oil 2.49 x 1012 0.279 x 1012 0. 0812 0.16 85 SN Base oil 7.20 x 1012 0.046 plus 0.3% DBPC 85 SN Base oil 120 x 1012 6. 10 x 1012 0.00403 0.04 plus 0.2% reaction product 85 SN Base oil 1.26 x 1012 6.50 x 1012 0.0041 0.04 plus 0.2% DBPC and 0.05% reaction product Example 6-Diesel Engine Oil 0.278% of the reaction product and well-known aminic and phenolic antioxidants were separately added to a typical diesel engine oil comprising base oil, detergents, dispersants and other additives. The onset oxidation temperatures were measured.

The results show that the reaction product is a better antioxidant than known anti-oxidants. SampleSampleOxidation Onset °C withoutantioxidant251Engineoil # Engine oil plus 0.278% IRGANOX L-57 263 Engine oil plus 0.278% NAUGALUBE 264 640 Engine oil plus 0.278% NAUGALUBE 268 #438L # Engine oil plus 0.278% HITECX710 263 Engine oil plus 0.278% reaction product 267 prepared above Example 7-NMR Spectroscopv The reaction product produced in Stage 1 above (the DMTD derivative) and the reaction product produced in Stage 2 above (the reaction product) were subjected to NMR spectroscopy on a Varian VXR-300 s instrument under the following running conditions: 25 °C with a CDC13 solvent (deuteriated chloroform).

The results as shown in peak intensity clearly demonstrate the significant change in functional groups, particularly at the frequency around 4.8-5.1 ppm, which intensity is absent prior to Stage 2 of the reaction. Differences also exist at the frequency around ppm where peak positions show significant shifts after the Stage 2 reaction.

Table-I Reaction Mixture Produced in Stage 1 SR. NO. INTENSITY FREQUENCY, PPM 7.2583134.158 2 46. 911 2.05140 3 54. 849 2.02576 4 36. 587 2.00318 1.99891526.602 6 13. 047 11.96717 7 40. 485 1.40320 8 47. 605 1.38465 1.37879955.805 Table-11 DMTD Derivative SR. NO. INTENSITY FREQUENCY, PPM 33.0697.270 31.0121.569 20. 279 1.517 147.9241.340 100.4291.319 105.7671.297 7 109. 75 1.286 8 179. 09 0.889 9 183. 25 0.8777 10 206. 98 0.87 Table-III Reaction Product Produced in Stage 2 SR. NO. INTENSITY FREQUENCY, PPM 1 38. 971 7.261 2 9. 570 5.861 3 14. 755 5.827 4 15. 387 5.804 5 12. 046 5.770 6 15. 180 5.023 7 19. 257 5.0158 8 17. 066 4.959 9 17. 600 4.946 10 15. 122 4. 939 11 15. 552 4.685 12 22. 6 2.0514 13 813. 337 1.259 14 173. 012 0.88074 Example 8-NMR Spectroscopy on Example 2 Example 2 was repeated using the reaction mixture from stage 1, the DMTD derivative and the reaction product from Stage 2, at a treat level of 0.2 % in each case. EX SAMPLE OXIDATION ONSET TEMPERATURE °C 1 MOBIL 150 SN BASE OIL 199.0 2 MOBIL 150 SN BASE OIL PLUS 203.0 THE RECTION MIXTURE PRODUCED IN STAGE 1 3 MOBIL 150 SN BASE OIL PLUS 205.0 THE DMTD DERIVATIVE 4 MOBIL 150 SN BASE OIL PLUS 223.0 THE RECTION PRODUCT PRODUCED IN STAGE 2 The results clearly demonstrate that the boost in onset temperature is not exhibited to the same extent prior to the production of the reaction product in Stage 2. The boost in oxidation onset temperature increases from 4 to 6 °C with the use of the reaction mixture produced in stage 1 and the DMTD derivative, as opposed to an increase in 24 OC with the use of the reaction product produced in Stage 2.

Example 9 Example 3 was repeated using the reaction mixture from stage 1, the DMTD derivative and the reaction product from Stage 2, at a treat level of 0.2 % in each case. EX SAMPLE COPPER CORROSION TEST RESULTS IP-154 1 MOBIL 150 SN BASE OIL PLUS 25 PPM 4 a SULPHUR POWDER 2 MOBIL 150 SN BASE OIL PLUS 25 PPM 3 b SULPHUR POWDER AND 0.2 % OF THE RECTION MIXTURE PRODUCED IN STAGE 1 3 MOBIL 150 SN BASE OIL PLUS 25 PPM 3 b SULPHUR POWDER AND 0.2 % DMTD DERIVATIVE 4 MOBIL 150 SN BASE OIL PLUS 25 PPM 2 d SULPHUR POWDER AND 0.2 % OF THE RECTION PRODUCT PRODUCED IN STAGE 2 The results clearly demonstrate that the excellent copper passivation exhibited by the reaction product produced in stage 2 is not exhibited to the same extent by the two ingredients used to produce the reaction product in Stage 2.